The Scruffy Astronomer

Focusing with a small Newt and a DSLR A slightly longer version of this is on the Optics Central blog page . One of the most common (and irritating) problems that owners of Newtonian telescopes have is getting a DSLR onto them – and actually get the image in focus. Well of course you want to take a photo! One of the most common (and irritating) problems that owners of Newtonian telescopes have is getting a DSLR onto them – and actually get the image in focus. Of course, people want to take photos of the Moon or other things when they’ve got a telescope and a DSLR – who wouldn’t? But actually getting the two things together is a little complicated. To make the physical connection, you need at least two things. First the telescope’s focuser has to have a specific thread (called a t-thread) cut into it. If your focuser doesn’t have one of these you can get a little tube with an eyepiece-shaped tube and the required thread. Second, you need an adapter called a t-ring, whi

Our recent competition for wide field astrophotography was won by Clint Conn, and I’ve attached his photo here. Stunning. I’ve taken a few in my time, but never this good. To take a photo like this, you can use a simple tripod and a camera. But you can’t expose for longer than about 30 seconds (depending on your focal length) before you start to get star trails. These can look nice, but if you don’t want them, it’s awful. You have to stop the stars’ apparent motion. A gigantic equatorial mount under your camera would do the job, but that's bulky and expensive. What's worse, your camera would look a bit ridiculous on top of a thumping great machine. You need a simpler and less expensive gadget that tracks the stars. There are several types out there, such as the Sky-Watcher Star Adventurer, or the Vixen Polarie.     You align them to the South Celestial Pole, and once they’re set up, they enable you to take photos of the sky using a camera and a normal lens. To d

Just about everyone in Australia is now familiar with having to live in and breathe this type of smoke. The 2019-20 bushfire season is a horror. The scale of the destruction of bush and agricultural land, let alone hundreds of buildings all around the country is impossible to estimate with any level of accuracy. Add to that the human toll and it's hard to comprehend. The smoke has been visible on satellite photos, and it’s even spread as far as New Zealand. I took this photo while walking in my local park. The smoke was particularly bad that morning, and the smell was unavoidable. That's the bush going up. Of course, above all that, the sun was shining. That morning we'd been greeted by a lurid sunrise. It was filtered so heavily the sun was easy to look directly at - not that I lingered, I've been well conditioned not to look at the sun. Of course, I can't help thinking in terms of photography, and on the way home I noticed the shadow I was casting seemed to have a

The other day I braved the heat and smoke and took our dog for a walk at my local park in Kew in Melbourne. I’d gone the day before and noticed that the place was thick with Lorikeets. They had been attracted by the park's redgums, some of which are currently flowering energetically.   Lorikeets love flowering gums and will make an incredible noise at dawn as they browse the flowers. For most of the year we only see Rainbow Lorikeets, which nest in the hollows.  For a few weeks each year, they’re joined by Musk Lorikeets, which have a subtly different call. Musk Lorikeets have a similar twitter to Rainbows, but they don’t have that occasional harsh squawk that the Rainbows do. After seeing the Lorikeets, I decided to go home and bring down my camera and binoculars – I’ve got a heavy pair of Nikon Monarch 8.5x56. I walked around the park, listening for Lorikeets. On a tangent, most birdos like 8 times magnification. The image stability is better, and you get a more complete idea of

Anne-Marie McComb has produced a fantastic demonstration of what extra time does for a faint image.  This emission nebula has a couple of different names, all of which are confusing. Officially, it’s known as Sharpless 2-308, but is known as the Dolphin Nebula. It really does look like a dolphin. Problem is, there’s another Dolphin Nebula out there, and that one is really hard to see from Australia. This nebula is typical of those formed by Wolf-Rayet stars. At an early stage in their lives, these stars act like most others, shedding material outwards as they age. However, something causes these stars to suddenly blow gas out at a far faster rate, and the fast-moving gas catches up with the slow-moving gas from before. That’s what causes the bubble-shaped nebulas. However, that’s not what Anne-Maree is trying to show. You’ll see that the two images here are similar, but one has far more of the dim details. This is all to do with signal-to-noise ratios. The longer exposure has more

Yes, you CAN find a meteorite! On the 4th of January this year, an Italian dog walker found a chunk of rock that had fallen from the sky three days earlier. How did he do this? He was looking for it after having been told it had landed in the area. January 1st, 18h 26min UT fireball trajectory calculated from the 8 PRISMA/FRIPON video detections. Credit: PRISMA/FRIPON This is the first meteorite that’s been found - in Italy at least - after a targeted search. Up until now, all meteorites have been found purely by accident. Across Italy and surrounding countries, there is an extensive (and growing) network of all-sky cameras, a bit like the ASV’s camera at their dark sky site (asv.org.au/lmro_skycam). These cameras are co-ordinated by the Italian National Institute of Astrophysics, and are placed to detect meteors. Together, the system is known as PRISMA (Prima Rete Italiana per la Sorveglianza sistematica di Meteore e dell’Atmosfera). When a meteor enters the atmosphere, it get

What’s this weird looking thing?   Every now and again, we get waifs and strays in the shop. The other day this one came in. Once upon a time it was a 90mm Maksutov Cassegrain spotting scope.  I find this sort of thing fascinating. When they’re pulled apart, you can see how the focus mechanism on a Cassegrain works. When you rotate the focus knob, the whole primary mirror moves away from or closer to the eyepiece. Here's a second photo of the mirror extended as far as it goes. With Cassegrains, it’s very important, when the focuser moves, that the mirror stays perpendicular to the light rays, or the image gets distorted. This is generally known a “mirror flop”. I’ve had a look at this one, and the mirror seems very stable. I haven’t been able to wobble it, even though it’s on a single shaft. I don’t want to mangle the scope any further, but I probably will later on. Larger Cassegrain telescopes often have locking mechanisms on the primary mirrors to stop the mirror moving und

Last month I went to the ASV’s Star-be-cue. The weather didn’t really play the game, and for most of the evening we were dodging clouds. But star parties are mostly social occasions, and a chance to meet up with other astronomers. They're also a good opportunity to see other people’s equipment and how they use it. While I was there, I got talking with a couple of people with a saxon Novo 909AZ3. They were watching M42 - the Great Nebula in Orion. Nearby, another group of people were also on M42 but through a saxon 8” Dobsonian. I had a saxon Hyperion 1021EQ3, so it was a great opportunity to compare scopes. The 909 and the 1021 produced very similar images. Although M42 was visible, it wasn’t very extensive. However, because these are both refractor telescopes, the “trapezium”, those four baby stars in the middle were sharp and bright, clearly separated from each other. The Dob gave a very different view. M42 was wide and very distinct. You could see wisps of it extending on b

Here in Oz, especially at this time of year, seeing conditions can really be degraded by the atmosphere. Heat haze can play havoc with your images, especially if you’re using an autoguider. Most recently, bushfire smoke has been awful, and the effect has been similar to very severe light pollution, with an orange or brown cast over colour photos. But Ian lives in Saskatchewan, which is in the Western part of Canada. It’s cold there. According to Ian, it was -16°C at the time. Yikes. Low temperatures can bring about beautiful viewing conditions, but they can have other unexpected side effects. This photo shows one of them.   Ian uses an ASI 1600 attached to a William Optics Z71 on a Sky-Watcher AZ-EQ6 (stop drooling, Bill!). While he was imaging the Jellyfish nebula, some approaching snow clouds caused changes in temperature and humidity, and these beauties appeared. They’re called light pillars. Ice crystals form in a large range of shapes. In the right conditions, they form in two-

Is it poor form that I’m not a huge fan of Venus as an object to watch in an evening? After all, its clouds prevent you from seeing any features on the planet’s surface, making it a less-than-totally-exciting sight. However, if you keep an eye on them over time, all planets do strange things, like change brightness or stop and go backwards every now and again. Venus is currently (January 2020) approaching its “maximum elongation” – that is, the furthest it gets away from the sun. That’s actually going to be a bit later this year, on 25 March. This diagram shows where Venus is going to be in January and again in April ( and yes, I know I mislabeled it 2019 rather than 2020 ), in relation to the Earth. About now, Venus is trailing the Earth, meaning it’s an evening object, and is nearly at its greatest distance away. It’s also showing most of its lit face to us. The word astronomers use is “gibbous”. Venus looking nearly round and pretty small isn’t a great sight. It’s bright, and w

  I guess most of you have heard about how Elon Musk’s SpaceX company has launched a second “train” of satellites, augmenting the ones sent up last month. The photos and videos look pretty freaky. You’ve probably also heard astronomers and astrophotographers moaning about it. Well, just how much of a problem is it? A quick answer is in my photo. I was up at the dark sky site a short while back, photographing the Horsehead nebula. Just as an aside, the Horsehead is my all-time favourite object, just pushing out the Fighting Dragons. I know it’s a lot of people’s favourite too – but it’s undeniably super cool. But I digress… I was taking five-minute sub-exposures using my three various narrowband filters. All up, I got about 50 of these for stacking, which I thought was a pretty good haul for a Summer night. But as you can see, I lost four of my subs to satellite photobombing. I’ve stacked the four frames I lost into this photo. I don't even think these are SpaceX satellites

You probably know that to get a good photo of a nebula through a telescope you need to use an exposure of a minute or more. This means your telescope’s mount needs to track the star – not just approximately, but precisely. There are some mounts that, once they’re set up correctly, will track beautifully. They do this by having high-tech sensors and magnetic drives which are near to perfect. The problem is that these mounts cost vast amounts of money. More reasonably priced mounts, like my NEQ6, are driven by gears. But even high-quality gears like this can’t be made perfect. Even if they're close, they get dirty, the lubricating grease moves around unevenly, or something else happens to the gears. As well, random wobbles occur. When this happens, the telescope shifts a tiny bit left or right, and it shows in your photo. For very wide-angle images, like those through a camera lens rather than a telescope, this is fine. But for telescopic images using high magnification scopes,